<!doctype html>
<html lang="zh-cmn-Hans">
<head>
    <!-- Required meta tags -->
    <meta charset="utf-8">`
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css" integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk" crossorigin="anonymous">
    <style>
        .my-container {
            width: 500px;
            height: 500px;
            background: #ddd;
            margin-bottom: 5px;
        }
    </style>
    <title>Hello, world!</title>
</head>
<body>
<h1>为要素配置颜色</h1>
<div class="">欢迎收看《小马技术视频》</div>
<div class="bg-primary text-white">欢迎收看《小马技术视频》</div>
<div class="bg-secondary text-white">欢迎收看《小马技术视频》</div>
<div class="bg-success text-white">欢迎收看《小马技术视频》</div>
<div class="bg-warning text-dark">欢迎收看《小马技术视频》</div>
<div class="bg-light text-dark">欢迎收看《小马技术视频》</div>

<h1 class="font-weight-normal display-4">文本样式</h1>
<div class="bg-info text-white">欢迎收看《小马技术视频》</div>
<div class="text-center bg-light font-weight-bold">欢迎收看《小马技术视频》</div>
<div class="text-left bg-light">欢迎收看《小马技术视频》</div>
<div class="text-right bg-light">欢迎收看《小马技术视频》</div>
<!--英文变换-->
<p class="text-lowercase">Lowercased text.</p>
<p class="text-uppercase">Uppercased text.</p>
<p class="text-capitalize">CapiTaliZed text.</p>

<h1>元素size变更</h1>
<div class="my-container">
    <div class="bg-primary w-50 h-50">小马视频</div>
</div>
<div class="my-container">
    <div class="bg-success w-75 h-100">小马视频</div>
</div>

<h1>余白和边框</h1>
<div class="my-container pt-2 pl-2">
    <div class="bg-primary w-50 h-50 pt-1 pl-2">小马视频</div>
</div>
<div class="my-container px-5 py-5">
    <div class="bg-success w-100 h-100">小马视频</div>
</div>

<h1>按钮的使用</h1>
<button>Yes</button>
<button class="btn">Yes</button>
<button class="btn btn-primary">Yes</button>
<button class="btn btn-danger btn-sm">Yes</button>
<button class="btn btn-success btn-lg">Yes</button>

<h1>网格布局</h1>
<div class="container">
    <div class="row mb-4">
<!--        mb表示网格的顶部 4表示顶部与下面的距离-->
        <div class="col-4 bg-danger">
            COL1
        </div>
        <div class="col-4 bg-success">
            COL2
        </div>
        <div class="col-4 bg-warning">
            COL3
        </div>
    </div>

    <div class="row">
        <div class="col-2 bg-danger">
            COL1
        </div>
        <div class="col-8 bg-success">
            COL2
        </div>
        <div class="col-2 bg-warning">
            COL3
        </div>
    </div>

    <div class="row mt-5">
        <div class="col-6 bg-danger">
            COL1
        </div>
        <div class="col-4 bg-success">
            COL2
        </div>
        <div class="col-8 bg-warning">
            COL3
        </div>
    </div>
</div>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js" integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI" crossorigin="anonymous"></script>
</body>
</html>